Plant volatiles

ABSTRACT

The present invention provides compounds and compositions for attracting or repelling sap-sucking insects, such as whitefly, as well as methods for using such compositions.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of Ser. No. 12/679,894,filed Jul. 1, 2011, which is the U.S. National Stage application ofPCT/NL2008/050617, filed Sep. 25, 2008, which claims the benefit andpriority of European Patent Application No. 07117153 0.2, filed Sep. 25,2007. The foregoing applications are incorporated by reference herein intheir entirety.

FIELD OF THE INVENTION

The present invention relates to the field of agriculture, in particularinsect pest control of plants. Compounds and compositions comprising oneor more volatile hydrocarbon compounds suitable for either repelling orattracting insect pests, such as whiteflies, are provided. Also providedare methods for making and using attractant or repellentcompounds/compositions and for controlling insect infestation and damagein the field and/or in greenhouses. The compositions are suitable forcontrolling plant insect pests, in particular sap-sucking insects of thesuborder Sternorrhyncha. Insects of the suborder Sternorrhyncha includepsyllids, whiteflies, aphids, mealybugs and scale insects and share acommon property, namely the utilization of plant sap as their foodsource. Other plant insect pests which can be controlled are thrips,mites (e.g. spider mites) and leaf hoppers. In a preferred embodimentmethods and compositions for controlling whitefly infestation andwhitefly damage of crop plants are provided. In a different embodiment,the compounds and/or compositions can be used for repelling insects ofthe family Culicidae, especially species belonging to the generaAnopheles (of which about 400 species exist, 30-40 of which transmitmalaria, such as the species of the A. gambiae complex), Culex and/orAedes. Also members of the family Ceratopogonidae, biting midges, can beattracted or repelled according to the invention, for examples thevertebrate blood sucking genera Culicoides, Forcipomyia (Lasiohelea),and Leptoconops, such as Culicoides impunctatus (the highland midge orScottish biting midge).

BACKGROUND OF THE INVENTION

Whiteflies of the genera Bemisia (sweet potato whitefly) andTrialeurodes (greenhouse whitefly) are major pests of crop plantsthroughout the world, causing economic losses especially due to thetransmission of plant viruses during feeding (i.e. they act as ‘virusvectors’). Bemisia tabaci is capable of transmitting more than 60different Geminiviridae plus a number of criniviruses, many of whichbelong to the Begomoviruses such as African cassava mosaic virus (ACMV),Bean golden mosaic virus (BGMV), Bean dwarf virus, Tomato yellow leafcurl virus (TYLCV), Tomato mottle virus (TMV), and others. Both tropicaland temperate crops are affected, such as tomatoes, beans, cucurbits,potatoes, cotton, cassava and sweet potatoes. To date, the main controlstrategy is the application of insecticides, aimed at killing adults,juveniles and eggs. Besides the substantial costs of insecticideapplication this practice has a severe environmental impact. Moreover,B. tabaci is difficult to control with insecticides due to emergingresistance to the active ingredients.

In order to reduce insecticide application, there is a need for new waysof controlling whitefly-induced crop damage and losses, both infield-grown and greenhouse-grown crops. From literature it is known thatvolatile components can directly influence insect behaviour (e.g. Bruceet al., 2005, Trends Plant Sci. 10: 269-74). One way to control virustransmission by whiteflies is by identifying insect repellents, whichcan be applied on or near the crop plants, and/or insect attractants,which can be applied on nearby areas to lure the insect pests away fromthe crop. The problem in identifying attractants and/or repellents isthat compounds that are known to attract one species may repel anotherspecies of insects. Often one cannot, therefore, draw conclusions aboutthe attractant or repellent properties of compounds or compositionsacross species which may differ in their sensory perception and feedingbehavior. Whiteflies, for example, investigate their host plants bylabial dabbing (using mechanosensors and chemosensors) on the epidermalsurface, before tapping into the vascular tissue (probing). Theirdecision at this point is influenced by e.g. constitutively producedrepellents but probably also by properties of the leaf surface.Preference is directly related to performance and virus transmission,which occurs upon probing. In order to avoid virus transmission, probingshould be prevented or at least reduced significantly. This meanscompounds that kill the whiteflies only after probing has occurred arenot suitable as crop protection agents, as the virus will already havebeen transferred. In addition, insect predators of whiteflies should notbe affected by the repellent or attractant, as these are useful inreducing the whitefly population.

Another problem in identifying suitable compounds and/or compositionsfor whitefly control lies in the fact that naturally occurring plantheadspace compositions and the content of the glandular trichomes ofplants contain a large number of different compounds in differentconcentrations, which vary between species and between individual plantlines or accessions within species. Even if a plant headspacecomposition as a whole is identified in having a certain effect oninsect pests, identifying which components, or combinations ofcomponents, may be suitable as attractants or repellents is no easy taskand to date there is no suitable repellent or attractant for whitefliesand other sap-sucking insect pests.

Zhang et al. (J. Econo Entomolog 2004, 97, p 1310-1318) tested 0.25%solutions of ginger oil as a repellent for B. argentifolii. In no-choicetests, only between 10.2 and 16.6% fewer adult whiteflies settled on thetreated plants and no difference was found in the numbers of eggs laidon the plants. Increasing the concentration of ginger oil was associatedwith phytotoxicity, thereby preventing an effective use of ginger oil aswhitefly repellent.

EP 0 583 774 describes the use of vegetable oil to reduce phytotoxicityof foliar insect control agents, whereby any type of insect controlagent may be used.

Glandular trichomes are prominent on foliage and stems of the genusLycopersicon (now classified as Solanum) and have been shown to producea large number of secondary compounds, such as sesquiterpenehydrocarbons, sesquiterpene acids, methylketones and sugar esters.Several studies have tried to correlate the density of glandulartrichomes with resistance against plant pests, such as maize earworm(Heliothis zea) or Colorado beetle (Kauffman and Kennedy, 1989, J ChemEcol 15, 1919-1930; Antonious, 2001, J Environ Sci Health B 36, 835-848and Antonious et al. 2005, J Environ Sci Health B 40: 619-631). Also themethylketones 2-undecanone and 2-tridecanone, stored in the glandulartrichomes of L. hirsutum f. glabratum were shown to exhibit a toxiceffect against fourth instar larvae of Colorado potato beetle and adultwhiteflies B. tabaci, respectively (Antonious et al. 2005, J Environ SciHealth B 40: 619-631).

Antonious and Kochhar (J Environm Science and Health B, 2003, B38:489-500) extracted and quantified zingiberene and curcumene from wildtomato accessions with the goal of selecting wild tomato accessions thatcan be used for the production of sesquiterpene hydrocarbons for naturalinsecticide production. However, whether such compounds are able to beused as whitefly repellents or attractants was not disclosed. It ismentioned that zingiberene has been associated with Colorado beetleresistance and beet armyworm resistance, while curcumene has beenassociated with insecticidal effects. The wild tomato species L.hirsutum f. typicum is mentioned to be resistant to B. argentifolii(Heinz et al. 1995, 88:1494-1502), but trichome based plant resistancecould, of course, have various causes and from this paper one cannotmake inferences regarding the presence or identity of compounds whichhave properties for attracting or repelling whiteflies.

Kostyukovsky et al. (Acta Horticulturae 2002, 576, 347-358) found thatfumigants of essential plant oils (Cineole, safrole, essential oil fromLabiatae or Foeniculum vulgare, or M-bromide) applied on pests of cutflowers (e.g. B. tabaci) at concentrations of 10-20 mg/l causedmortality after 2-4 hours of exposure (see Table 5).

Freitas et al. (Euphytica 2002, 127: 275-287) studied the geneticinheritance of the genes for the production of both the sesquiterpenezingiberene and glandular trichome types I, IV, VI and VII ininterspecific crosses between L. esculentum (cultivated tomato, low inzingiberene) and wild L. hirsutum var. hirsutum (high in zingiberene).Zingiberene content in F₂ plants contributed to B. argentifoliiresistance by correlation and it was suggested to breed plants withsimultaneously high levels of zingiberene, 2-tridecanone and/oracylsugars to contribute to higher levels of whitefly resistance.However, breeding for pest resistance is fundamentally different fromdeveloping pest repellent or attractant compositions. There is noindication as to the use of synthetic or purified zingiberene aswhitefly repellent as such or in combination with other compounds.

SUMMARY OF THE INVENTION

The present inventors found 10 terpenes (or terpene analogues) to berelated to repellance/attractance of sap-sucking insect pests, inparticular whiteflies. These compounds can be used individually or incombination to make effective insect repellent and/or insect attractantcompositions. Provided are insect repellent compositions (in particularrepelling sap-sucking insect pests of crop plants, preferably whitefly)comprising or consisting of one or more of the following sevencompounds: curcumene, especially alpha-curcumene (sesquiterpene),myrcene, especially beta-myrcene (monoterpene), cymene, especiallypara-cymene (hydrocarbon related to monoterpene), terpinene, especiallygamma-terpinene (monoterpene) and/or alpha-terpinene (monoterpene),zingiberene (sesquiterpene) and/or phellandrene, especiallyalpha-phellandrene (monoterpene) as well as methods of using these anddispensers or other containers or supporting material comprising these.

Provided are insect attractant compositions (in particular attractingsap-sucking insect pests of crop plants, preferably whitefly) comprisingor consisting of one or more of the following three compounds:Phellandrene, especially beta-phellandrene (monoterpene), limonene (theD- and/or L-isomer) (monoterpene) and/or 2-carene (monoterpene), as wellas methods of using these and dispensers or other containers or materialcomprising these.

In a further embodiment of the invention the above repellent orattractant compounds or compositions are used to attract or repelinsects of the family Culicidae (order Diptera) and/or Ceratopogonidae,especially blood sucking insects that are irritant and potentiallytransmit diseases to humans and animals, such as mosquitoes.

GENERAL DEFINITIONS

“Plant insect pests” or “plant pests” or “insect pests” or “plant pestspecies” are insect species that cause infestation and damage on cropand/or ornamental plants (hosts plant species), by infestation of theplants or plant parts. An “infestation” is the presence of a largenumber of pest organisms in an area (e.g. a field or glasshouse), on thesurface of a host plant or on anything that might contact a host plant,or in the soil. Insect pests include sap-sucking insect pests (seebelow), but also other insect pests, such as thrips, cicada, mites (e.g.spider mites and others) and leaf-hoppers.

“Mammalian insect pests” or “mammalian disease vectors” refer herein toinsects of the order Diptera which are blood-sucking/biting insects andare potentially able to act as vectors of human and/or mammaliandiseases (but not necessarily, they may just be irritating), such asmalaria. When referring to “insect pests” herein, it is understood thatthe parts of the document also apply to insects attacking animals,especially mammals, in an analogous way to plant pests, except thatthese are blood sucking/biting insects.

“Sap-sucking insect pests” include plant pests of the suborderSternorrhyncha (of the order Hemiptera, of the class Insecta), i.e.insect pests which include psyllids, whiteflies, aphids, mealybugs andscale insects and share a common property, namely the utilization ofplant sap as their food source.

“Aphids” include herein plant insect pests of the family Aphididae, suchas Aphis gossypii, A. fabae, A. glycines, A. nerii, A. nasturtii, Myzuspersicae, M. cerasi, M. ornatus, Nasonovia (e.g. N. ribisnigri),Macrosiphum, Brevicoryne and others.

“Insect vectors” are insects that are capable of carrying andtransmitting viruses to plants. In the context of mammalian diseasevectors, insect vectors are insects which attack mammals and canpotentially transmit diseases to mammals, such as mosquitoes, which areable to transmit the parasite Plasmodium to humans or heartworm tocanines.

“Whitefly” or “whiteflies” refer to species of the genus Bemisia,especially B. tabaci and B. argentifolii (also known as biotype B of B.tabaci), and/or species of the genus Trialeurodes, especially T.vaporariorum (greenhouse whitefly) and T. abutinolea (banded wingedwhitefly). Included herein are all biotypes, such as biotype Q and B ofB. tabaci, as well as any developmental stage, such as eggs, larvae,pupae and adults.

“Repellent” compound or composition refers to one or more compounds,which repel one or more insect pest species (e.g. whiteflies), andsignificantly reduce the infestation and/or damage caused by the insectpest (e.g. whiteflies) in the area and/or surfaces applied, compared tothe same area and/or surfaces not treated with the repellent (measuredat one or more time points after repellent application). A “significantreduction” is a reduction by at least 5 number %, preferably at least10%, 15%, 20%, 30%, 50%, 60%, 70%, 80%, 90%, 95% or more (100%).Infestation and/or damage caused by the insect pests(s) (e.g. bywhitefly) can be measured in various ways, e.g. by assessing the planthealth or by assessing e.g. insect pest numbers, insect eggs laid,insect probing of the tissue, virus transmission or incidence, yieldlosses, plant tissue damage, or any other direct or indirect symptoms ofinsect infestation/damage, etc. In the context of mammalian insectpests, for example the number of insects, insect bites or diseasesymptoms can be used to assess and/or quantify the effect.

“Attractant” compound or composition refers to one or more compounds,which attract one or more insect pest species (especially sap-suckinginsect pests, such as whiteflies) and significantly increase the numberof the pest organisms (e.g. whiteflies) in the area and/or surfacesapplied, compared to the same area and/or surfaces without theattractant (measured at one or more time points after attractantapplication). A “significant increase” is an increase by at least 5number %, preferably at least 10%, 15%, 20%, 30%, 50% 60%, 70%, 80%,90%, 95%, or more. When the attractant is applied to plant tissues, theattractant effect can be measured in various ways, for example byassessing the number of insects at one or more time-points afterapplication of the attractant, or by assessing tissue damage or othersymptoms associated with insect infestation/damage. When the attractantis applied to other supporting materials, such as non-biologicalmaterials/areas (traps, solid supports, etc.), the numbers of insects onthe treated versus the non-treated material/areas is assessed. In thecontext of mammalian insect pests, for example the number of insects canbe used to assess and/or quantify the effect (attraction).

An “effective amount” of a repellent compound or composition refers toan amount sufficient to significantly decrease the infestation and/ordamage caused by insect pests (especially by one or more sap-suckinginsect pests such as whiteflies) on treated plants compared to untreatedplants. In the context of mammalian insect pests, an effective amount ofa repellent compound or composition refers to an amount sufficient tosignificantly repel the insects as defined above.

An “effective amount” of an attractant compound or composition refers toan amount sufficient to significantly increases the number of insectpests (especially by one or more sap-sucking insect pests such aswhiteflies and/or stages thereof, e.g. eggs laid) in the treated area oron the treated surfaces compared to the untreated area or surfaces. Inthe context of mammalian insect pests, an effective amount of arepellent compound or composition refers to an amount sufficient tosignificantly attract the insects as defined above.

“Active ingredient” refers to the ingredient/s in a formulation whichis/are biologically active, e.g. insect vector/pest repellents orattractants. “Inert ingredient” or “inactive” refers to ingredientswhich are not biologically active (at least regarding the target insectvectors), such as carriers of the active ingredient(s), e.g. water, oilor oil-based carriers, solvents, etc.

“Solvent” is a liquid that dissolves a solid, liquid, or gaseous solute,resulting in a solution, dispersion or emulsion.

“Traps” refer to materials to which an effective amount of an attractantcompound or composition is applied. Generally a trap may be a pluralityof plants (trap-crop or trap plants) or a container (e.g. an insecttrap) or surface or liquid to which the attractant compound orcomposition is applied, so that the insects are lured towards orinto/onto the trap. The attractant compound or compositions may also bereferred to as “bait formulation”.

“Insecticides” or “insecticidal” refers to compounds or compositionsthat (in contrast to repellents) kill or inactivate one or more stagesof an insect (ovicides, larvicides, adulticides, etc.), i.e. they affectmortality rather than distribution of the insects.

‘Insect-pest predators or “insect-pest parasites” refer herein toorganisms that feed on or parasitize the insect pest. For example“whitefly predators” or “parasites” refer herein to organisms, such asinsect species, which reduce whitefly numbers by predation and/orparasitism, such as broad mite (Polyphagotarsonemus latus), Swirski-mite(Amblyseius swirskii), lacewings, various beetles, etc., or parasiticwasps (such as Encarsia and Eretmocerus spp.).

“Host plant(s)” refer to one or more species which are natural hostspecies of insect pests. Whitefly, for example, has a broad host range,such as, but not limited to, tomato, pepper, eggplant, lettuce, Brassicaspecies, such as oilseed rape, broccoli, cauliflower and cabbage crops;cucurbits such as cucumber, melon, pumpkin, squash; peanut, soybeans,cotton, beans, cassava, potatoes, sweet potatoes and okra. Alsoornamental species are among the preferred hosts, such as hibiscus,poinsettia, lilies, iris, lantana rose and petunia.

“Crop” or “crop plants” or “cultivated plants” refer to plants which aregrown by humans for various purposes, such as but not limited toobtaining food-, feed- or any other ingredient from the plants or plantparts, including plant-derived products such as oil, carbohydrates,medicinal ingredients, etc., but also including plants cultivated forornamental purposes or for socio-economic purposes, such as lawns(grass-grown areas) of e.g. golf courses, playgrounds or parks, orplants grown in forests or parks, etc. Crop plants may be grown in thefield, in gardens, in greenhouses or any other way, and they may begrown on a small or on a large scale.

Recently tomato has been reclassified into the Solanum genus. Throughoutthis document “Lycopersicon esculentum” and “Solanum lycopersicum” areused interchangeably to refer to cultivated tomato plants. Similarly,when referring to wild tomato the Lycopersicon pennelli and Solanumpennelli, as well as Lycopersicon hirsutum f. glabratum and Lycopersiconhirsutum f. typicum and Solanum habrochaites, are used interchangeably.Similarly, when referring to wild Lycopersicon species, it is understoodthat these are now re-classified as belonging to the genus Solanum andthese genera designations are used interchangeably.

“Terpenes” are hydrocarbons having a carbon skeleton derived fromisoprene units and are subdivided into groups based on their carbonnumber, e.g. C10 monoterpenes, C15 sesquiterpenes, C20 diterpenes, C25sesterterpenes, C30 triterpenes, C40 tetraterpenes and C5n polyterpenes.They are herein generally referred to by their trivial names, as e.g.described in Kirk-Othmer, Encyclopedia of Chemical Technology, 4^(th)Ed., Vol. 23, pages 833-882, 1997. The term “terpene(s)” as used hereinalso includes compounds commonly known as “terpenoids”, terpene and/orterpenoid analogues, such as alcohols, esters, aldehydes and ketones,(natural or synthetic) isomers, and where applicable stereoisomersand/or tautomers of any of these. When referring to specific isomersherein (such as alpha and/or beta isomers), it is understood that otherisomers are included and that the other isomers or mixtures of isomerscan substitute for the isomer specifically mentioned, as long as theseare functional.

Monoterpenes may further be distinguished by the structure of the carbonskeleton and may be grouped into “acyclic monoterpenes” (e.g. myrcene,(Z)- and (E)-ocimene, linalool, geraniol, nerol, citronellol, myrcenol,geranial, citral a, neral, citral b, citronellal, etc.), “monocyclicmonoterpenes” (e.g. limonene, alpha- and gamma-terpinene, alpha- andbeta-phellandrene, terpinolene, menthol, carveol, etc.), “bicyclicmonoterpenes” (e.g. alpha-pinene, beta-pinene, myrtenol, myrtenal,verbanol, verbanon, pinocarveol, etc.) and “tricyclic monoterpenes”(e.g. tricyclene). See Kirk-Othmer, Encyclopedia of Chemical Technology,4^(th) Ed., Vol. 23, pages 834-835, 1997.

In this document and in its claims, the verb “to comprise” and itsconjugations is used in its non-limiting sense to mean that itemsfollowing the word are included, but items not specifically mentionedare not excluded. In addition, reference to an element by the indefinitearticle “a” or “an” does not exclude the possibility that more than oneof the element is present, unless the context clearly requires thatthere be one and only one of the elements. The indefinite article “a” or“an” thus usually means “at least one”.

Whenever reference to a “plant” or “plants” (or a plurality of plants)is understood to also refer to plant parts (cells, tissues or organs,seeds, severed or harvested parts, leaves, seedlings, flowers, pollen,fruit, stems, roots, callus, protoplasts, etc), progeny or clonalpropagations of the plants which retain the distinguishingcharacteristics of the parents, such as seed obtained by selfing orcrossing, e.g. hybrid seed (obtained by crossing two inbred parentallines), hybrid plants and plant parts derived therefrom are encompassedherein, unless otherwise indicated.

DETAILED DESCRIPTION

The invention relates in one embodiment to compounds, and compositionscomprising or consisting of one or more of these, which have insectrepellent or insect attractant properties.

Compounds and Compositions

Whiteflies make use of both visual cues and chemical cues to find theirhost plant. In free choice recapture-assays with tomato plants, whereinvisual cues were removed, it was found whiteflies had a preference forthe cultivated L. esculentum (cultivar Moneymaker) over various wildtomato species (Solanum pennelli, LA716; Solanum habrochaites f.typicum, PI27826; Solanum habrochaites f. glabratum, also referred to asL. hirsutum f. glabratum; PI126449). When the headspace of wild tomatoplants was removed, dissolved in pentane-ether and added (on afilter-paper carrier) to the cultivated Moneymaker, this cultivar becameup to 60% less attractive to whiteflies (B. tabaci, biotype Q), whilethe application of the control (the solvent pentane-ether) had no effecton attraction/repellency. See Example 1.

In a large experiment (see Example 2), the headspace of 16 wild tomatoaccessions and 5 cultivated tomato lines were sampled and analyzed (6repeats). In total 51 compounds were identified to be present in thecaptured headspace. Furthermore, the level of repellency/attraction ofeach of the 21 tomato accessions was established in free choicebioassays with B. tabaci (biotype Q), using a ranking scale of 1-7(1=highest repellency to 7=lowest repellency). Next, the identifiedvolatile compounds were correlated to the repellency/attraction score ofeach tomato accession through a linear regression analysis. Eventually 7volatile components were found to be related to whitefly repellence and3 volatile components were shown to be correlated to whitefly attraction(Table 1).

TABLE 1 Volatile aromatic hydrocarbons Volatile compound (common Effecton Chemical structure, chemical name, name) insects (CAS Registrynumber) alpha- curcumene Repellent

1-(1,5-Dimethyl-4-hexenyl)-4- methylbenzene (644-30-4) beta- myrceneRepellent

1,6-Octadiene,7-metyl-3-methylene (123-35-3) para- cymene Repellent

benzene, 1-methyl-4-(1-methylethyl) (99-87-6) gamma- terpinene Repellent

1,4-cyclohexadiene, 1-methyl-4-(1- methylethyl)-(99-85-4) zingibereneRepellent

1,3-Cyclohexadiene, 5-(1,5-dimethyl-4- hexenyl)-2-methyl-(495-60-3)Alpha- terpinene Repellent

Alpha- phellandrene Repellent

beta- phellandrene Attractant

methy1-6-(1-methylethyl)cyclohexene<3-> (555-10-2) limonene Attractant

methy1-4-(1- methylethenyl)cyclohexene<1-> (138-86-3) 2-careneAttractant

bicyclo [4.1.0] hept-2-ene, 3,7,7- trimethyl- (554-61-0)

The whitefly repellent or attractant properties of the individual, purecompounds described in Table 1 (chemically synthesized or bought fromcommercial suppliers) were confirmed in bioassays (Example 3). Further,mixtures of two or more repellents or two or more attractants are testedfor efficacy and possible synergistic effects. A direct link between B.tabaci response and the (individual or mixtures of) compounds of Table 1is confirmed in antennae-electrophysiological experiments using anadapted Olfactory Detector Port (Example 4). In this way the individualvolatile compounds of Table 1, or mixtures of two or more compounds ofTable 1, are put into direct contact with the antennae of the whiteflythrough electrodes and a EAD-potential (Electro-antennographicdetection) is established.

The above findings can be extended to other insect pests, such as othersap-sucking insects, thrips, mites and others, such as mammalian insectpests. Thrips include for example Thrips tabaci, Frankliniellaoccidentalis, Thrips fuscipennis, Echinothrips americanus and others.Mites include for example the so called spider mites (familyTetranychidae), thread-footed mites (family Tarsonemidae), and the gallmites.

Thus, in one embodiment the present invention provides an insectrepellent (especially a sap-sucking insect repellent, a thrips and/or amite repellent, preferably at least a whitefly repellent) compositioncomprising or consisting of an effective amount of one or more of:alpha-curcumene, beta-myrcene, para-cymene, gamma-terpinene,alpha-terpinene, alpha-phellandrene and/or zingiberene.

Combinations of two or more repellent compounds include the followingpreferred combinations:

-   -   epizingiberene in combination with S-curcumene;    -   beta-myrcene in combination with para-cymene and/or gamma or        alpha terpinene, S-curcumene and/or zingiberene;    -   para-cymene and beta-myrcene and/or gamma-terpinene;    -   para-cymene and alpha-terpinene and/or alpha-phellandrene;    -   any combination of 2, 3, 4, 5, 6 or 7 of the repellent        compounds, whereby the combination preferably does not occur in        nature and/or does not occur in the purity (absence of other        compounds), concentration and/or ratios provided herein;

In another embodiment the present invention provides an insectattractant (especially a sap-sucking insect attractant, thrip and/ormite attractant, preferably at least a whitefly attractant compositioncomprising or consisting of an effective amount of one or more of:beta-phellandrene, limonene and/or 2-carene. Combinations of two or moreattractant compounds include therefore the following combinations:

-   -   beta-phellandrene and limonene;    -   beta-phellandrene and 2-carene;    -   limonene and 2-carene; and    -   beta-phellandrene limonene and 2-carene.

For one or more different insect pests the ranking of the abovecompounds with respect to their attraction or repellence effect mayvary. Which of the 7 repellent compounds is individually most effectiveas repellent of one or more insect pests, and which of the 3 attractantcompounds is individually most effective as attractant of one or moreinsect pests (preferably sap-sucking insects pests, thrips and/or mites;most preferably at least whitefly), can be tested in bioassays asdescribed elsewhere herein or as adapted therefrom.

Similarly, which combinations of two or more compounds selected fromeither the 7 repellents or from the 3 attractants are most effectivewith respect of attracting or repelling one or more insect pests can betested without undue experimentation using a bioassay, as describedelsewhere herein. A synergistic combination is a combination where theeffect of applying the compounds together (e.g. as a mixture orconsecutively to the same area) is larger than the effect achieved whenapplying the compounds individually.

When mixtures of two compounds are used, various ratios may be mosteffective in attracting or repelling one or more insect pests. Ratioswhich may be suitable are 100:1, 50:1, 10:1, 5:1, 2:1, 1:1, 1:2, 1:5,1:10, 1:50, 1:100 or any ratio in between.

When mixtures of three compounds are used, suitable ratios may include1:1:1, 1:2:1, 1:2:2, 1:10:10, etc. See also Table 3 for suitable ratios.The skilled person will be able to determine which ratio is the mostsuitable for a particular insect species.

In one embodiment of the invention the composition comprising orconsisting of (an effective amount of) at least one, two, three or moreof the attractant or repellent compounds selected from the above groupis substantially (i.e. >90%, especially >95%, >98% or >99%) orcompletely (i.e. 100%) free of other, not selected terpene or terpenoidcompounds, especially non-selected terpene and/or terpenoid compoundsproduced naturally by plants. The compositions thus comprises as activeingredient(s) only effective amounts of the selected compounds orcombination of compounds. The compositions are, therefore not naturalheadspace compositions of plants (i.e. as occurring in nature asheadspace of non-transgenic plants, such as cultivated or wild plants),as these natural headspace compositions contain a large variety ofterpenes and terpenoids. These natural headspace compositions may varyover time and under different environmental conditions. In contrast, thecompositions according to the invention are defined compositions.

The compounds may be made by chemical synthesis (Millar et al., 1998, J.Nat. Prod 61:1025-1026) or may be purified from natural sources, such asplants, plant tissue(s) or headspaces, using methods known in the art,such as distillation (Agarwal et al., 2001, Pest Man. Sci., 57:289-300),in vivo production (Colby et al., 1998, PNAS 95: 2216-2221; Chang etal., 2007, Nat. Chem. Biol., 3: 274-277) and/or conventional solventextraction, as e.g. commonly used for obtaining components ofessential/ethereal oils from plants (see e.g. Peng et al., 2004, J.Chromatogr. A., 1040: 1-17; Eikani et al., 2006, J. Food Eng., 80:735-740; Durling et al., 2006, Food Chem., 101:1417-1424). Fordistillation raw plant material e.g. leaves, roots, flowers, fruit peel,etc. is placed into a distillation apparatus above water and heated. Thesteam vaporizes the volatiles, and the vapor is condensed and collected.The distillate can then be fractionated further (e.g. by solventextraction) or enriched for specific compounds. Alternatively, thestarting material comprises mainly the volatile to be purified.

Solvent extraction from tissues uses for example hexane or supercriticalcarbon dioxide and/or ethyl alcohol to extract the volatiles, optionallyin combination with distillation steps. Headspace volatiles may also beextracted using solvents, such as pentane ether.

As preferably relatively pure compounds are used, i.e. compounds free ofplant tissue, waxes, resins or other plant-derived contaminants, as wellas substantially free of non-desired terpenes, it is preferred to usesynthetic compounds and/or recombinantly produced compounds and/orsubstantially purified compounds. Thus in one embodiment of theinvention, each of the individual compounds is “substantially pure”,whereby less than 10%, more preferably less than 5%, preferably lessthan 3%, 2% or 1% of contaminants, such as non-desired hydrocarbons,proteins, waxes, resins, DNA, RNA, sugars, cell walls, or otherplant-components, are present.

The compounds can be also be obtained from commercial suppliers, such asSigma-Aldrich (see www.sigmaaldrich.com). For example, beta-myrcene(Sigma-Aldrich product no: 64643, ≧95% purity), para-cymene(Sigma-Aldrich product no: 30039, ≧99.5% purity) and gamma-terpinene(Sigma-Aldrich product no: 86476, ≧98.5% purity) are available fromSigma-Aldrich, as is (+)-limonene and (−)-limonene or both enantiomeres(Sigma-Aldrich product no: 62118, 62128, 89188) and (+)2-carene(Sigma-Aldrich product no: 21984), alpha-phellandrene (Sigma-Aldrichproduct number 77429, ≧95% purity) and alpha-terpinene (Sigma-Aldrichproduct no: 88473, ≧95% purity). Zingiberene and curcumene can also beisolated from ginger oil, e.g. by chemical modification and subsequentdistillation as described by Millar (1998, J. Nat. Proc. 61: 1025-1026).Compounds, such as beta-phellandrene, can be synthesized chemically denovo (see e.g. U.S. Pat. No. 4,136,126).

It is also possible to produce the above monoterpene and/orsesquiterpene compounds in recombinant microorganisms, such as bacteria(e.g. E. coli) or fungi (e.g. yeasts, such as Pichia or Hansenula). Theexpression of one or more genes in microorganisms, preferably withsecretion of the compound into the growth medium, allows largerquantities and cheaper production of pure compounds (free of othermonoterpenes and sesquiterpenes) to be made. For example WO2006/065126describes terpene hydroxylation, whereby e.g. limonene can be producedfrom suitable substrates in microbial hosts expressing a cytochrome P450enzyme. See also Reiling et al. (Biotechnol. Bioeng. 2004, 87: 200-212),describing production of mono- and di-terpenes in E. coli.

The compounds and/or compositions comprising, or consisting of, one ormore of these may be in the form of a volatile/gas, a liquid, asemi-solid (e.g. gel beads, creams, foams, etc.) or as a solid(granules, powders, etc.). They may, thus contain an inert carrier, suchas a solvent, for example an alcohol (e.g. ethanol) or ether (e.g.pentane ether) or another organic solvent (e.g. hexane), which doespreferably not have any effect on whitefly behavior. Instead of beingdissolved in a solvent, such as alcohol or alcohol mixture or ether,also oil-based carriers may be used. Water is generally not a verysuitable carrier, as miscibility of these lipophilic compounds in wateris low or absent. The formulation of the compound(s) should be in such away that it is easily applied to the target location and that the insectbehavior is affected (and preferably that the insect distribution in theapplied area is significantly affected). The repellent compounds and/orcompositions are in one embodiment applied to a plurality of cropplants, while the attractant compositions are preferably applied to alocation distinct from the crop plants, e.g. a boarder trap-crop or traprows, interplanted between with the crop rows. When applied to plants,e.g. in the field or in greenhouses, a gas, liquid (e.g. whichevaporates upon contact with air) or semi-solid form may be preferred,which can be sprayed or dispersed onto the aerial plant surface. Solidformulations include granules, powders, slow-release matrices (e.g.coatings or matrices surrounding the active ingredient and releasing theingredient slowly), etc. The active ingredient and carrier (e.g. thesolvent) may also be placed into a solid container, such as rubber septa(commercially available), from which the volatiles are released slowly.

However, all types of formulations are envisaged herein for both theattractant-formulations and the repellent—formulations according to theinvention. The skilled person will know how to make an appropriateformulation, taking the following factors into consideration: 1. percentof active ingredient, 2. ease in handling and mixing, 3. safety forhumans and non-target animals (such as insect pest predators orparasites), 4. environment where the formulation is to be applied(field, greenhouse, etc.), 5. habits of the target insect (e.g.whiteflies and/or other insect pests), 6. the crop to be protected andpossible injury to the crop. Generally, formulations suitable for plantpesticides can be used or adapted for making a repellent- or attractantformulations according to the invention. Types of formulations includethe following:

-   -   a) Emulsified Concentrates (EC) formulations, which are liquid        formulations wherein the active ingredient(s) is/are dissolved        in oil or another solvent and wherein an emulsifier is added so        that the formulation can be mixed with oil or water for        spraying.    -   b) High concentrate liquids, spray concentrates and ULV's (ultra        low volume concentrates), which contain high concentrations of        active ingredient(s) and are generally diluted by mixing with        oil or water, or are used without dilution directly.    -   c) Low concentrate liquids or oil solutions, which generally        require no further dilution and comprise the active        ingredient(s) in the appropriate application dosage.    -   d) Flowable liquids can be made for active ingredients that do        not dissolve well in water or oil. The active ingredient is a        solid, which is ground or in fine powder form. The fine solid is        then suspended in liquid (together with suspending agents,        adjuvants and/or other ingredients).    -   e) Solutions, or water soluble concentrates, which are liquid        formulations, made by dissolving the active ingredient(s) in a        solvent (e.g. water or organic solvents).    -   f) Encapsulated formulations, whereby the active ingredient/s        is/are contained in small capsules or coatings, which in turn        can be for example suspended in a liquid (e.g. to be sprayed).    -   g) Dust formulations, which are applied dry. They include the        active ingredient(s) as solid, e.g. finely ground, optionally        mixed with other powders, such as talc, etc.    -   h) Granules, which are made of dry, porous material to which the        active ingredients have been applied. Often granule formulations        are applied to the soil, but they can also be applied to the        plants.    -   i) Wettable powders, which are dry, powdered formulations. In        contrast to Dust formulations, wetting agents and/or dispersing        agents are present in the formulation. Often they contain higher        concentrations of active ingredients than Dust formulations,        e.g. 15%-95% active ingredient.    -   j) Soluble powders, which are similar to wettable powders, but        dissolve completely in solution.    -   k) Dry flowables, which look like granules, but are used in the        same way as wettable powders.    -   l) Liquefied gas and/or fumigants, which are liquefied volatiles        or gaseous formulations. Certain volatiles can form liquids e.g.        under pressure, and will turn into vapors (volatiles) again        under certain conditions, e.g. once the pressure is released.        The vaporized active ingredient (volatile) will have the desired        effect upon release. The formulations may be released into the        soil or under coverings, such as tarps (canvases), or into        (relatively) closed environments. The (liquefied or gaseous)        active ingredient may also be incorporated into capsules, gels        or other matrices which slowly release the vaporized active        ingredient into the atmosphere.    -   m) Bait formulations refer to formulations which contain one or        more attractant compounds according to the invention.        Optionally, they may contain other attractants or even compounds        toxic to the target insect species and/or to other insect        species, for example they may contain one or more insecticides,        which kill the target insect (and/or other insects), e.g. the        whiteflies, when ingested or upon contact. Such toxins need not        be contained in the attractant formulation as such, but can also        be applied to the target area or target plants as a separate        component (e.g. before, after or together with the attractant        compound or composition). Such a kit of compositions is also an        embodiment of the invention.    -   n) Aerosols are gaseous formulations stored under pressure, e.g.        in a can.

Formulations under 1) above are especially preferred herein.

Formulations may also be similar to those used for the insect repellentDEET™ (N,N-diethyl-m-toluamide or N,N,-diethyl-3-methylbenzamide),especially when mammalian disease vectors are to be repelled. DEET™ isavailable in >200 formulations, such as aerosol sprays, non-aerosolsprays, creams, lotions, foams, sticks, controlled release formulations(encapsulated in protein), etc., with the active ingredient ranging from4-100%. See also U.S. Pat. No. 4,774,082 and U.S. Pat. No. 6,180,127 forvolatile insect repellent formulations and slow release formulations.

Similarly, formulations as commonly used for volatile herbicides (e.g.volatile ester herbicides) may be used herein see e.g. U.S. Pat. No.3,725,031 or Day, Weed Research, Volume 1, Issue 3, Page 177-183,September 1961, describing volatile, leaf applied, formulations ofDalapon to reduce soil contamination.

Optionally other components may be added to the active ingredient (therepellent(s) or attractant(s)), such as nutrients, osmotic agents, oneor more suitable carriers, diluents, emulsifiers, wetting agents,surfactants, dispersants, adjuvants, volatiles, stabilizers, etc.“Carrier” refers to compounds which are combined with the activeingredient(s) but which themselves have no significant biologicalactivity, at least not on the target insect species, such as whiteflies.Preferably, the carriers used have also no negative biological effectson plants, e.g. the host crop, i.e. they preferably have no, or minimal,phytotoxicity. Carriers may be gases, liquids (e.g. volatile liquids) orsolids and they may be water, oil, oil-comprising solutions (e.g.emulsions), solvents, etc.

The percentage of active ingredient in the final attractant or repellentcomposition may vary considerably, depending on the activity of theactive ingredient(s), the type of formulation, site and mode ofapplication, etc. The percentage of active ingredient(s) may thus be atleast about 1%, 2%, 5%, 10%, 30%, 50%, 70%, 80%, 90%, 95% or even 100%weight per volume of the composition.

Thus, a composition comprising one or more active ingredients (one ormore repellents or one or more attractants) can be applied to the plantsor area to be treated e.g. by spraying or by vaporisation from acarrier. Also, repellent compositions can be placed (e.g. on carriers)in between the plants while the composition comprising or consisting ofone or more attractants are preferably placed in/on traps or in/onlocations nearby the plants which are to be protected.

The compositions according to the invention may also comprise otherbiologically active compounds, such as other insect attractants orrepellents known in the art, insecticides, etc. Also, different stagesof the target insect may be more susceptible to one compound than toanother, and compounds (according to the invention and/or compoundsknown in the art) which target different stages of a pest species may becombined. Similarly, different pest species may be targeted by combiningeffective amounts of compounds (according to the invention and/orcompounds known in the art) for each of the pest species.

Repellent or attractant compositions may further comprise insecticides,herbicides (if the host plant to be treated is herbicide resistant, e.g.transgenic herbicide resistant plants), fungicides and/or otherbiologically active ingredients, such as growth enhancing agents,safeners, fertilizers, etc.

Insect attractants compositions may also contain one or moreinsecticides in order to kill insect survival and/or reproduction. Alsoinsect pheromones, which attract the target insect (e.g. whiteflies),may be added to the attractant compositions. Similarly, attractants ofpredators of the target insect(s) may be comprised in the compositions.

Preferably, the compositions do not contain substances which havenegative biological effects on plants (e.g. the host crop or trapplant), i.e. they preferably have no, or minimal, phytotoxicity on host-and/or trap-plant species. Phytotoxicity of individual components orcompositions can be easily tested by contacting the components orcomposition with plant tissue, e.g. leaves. Also, the compositionspreferably have no negative effect on non-target insects, such aspredators of whitefly.

An effective amount for attracting or repelling the target pest, e.g.whiteflies, should be present in the composition. Suitable amounts areprovided (especially for whiteflies, but not limited thereto) in Table2, below. Suitable amounts may range from at least about 0.5, 1, 2, 3, 4or 5 μg volatile compound released in 24 h to at least about 10, 20, 30,50, 100, 200, 300, 400, 500, 600, 800, 900 or 1000 μg or more of thevolatile compound being released per 24 hours, or equivalents thereof.Suitable amounts may also be expressed as amounts per kg biomass (freshweight) to be treated, and range from e.g. at least about 0.01 mgcompound per kg biomass per 24 hours to at least about 60, 70, 80, 90 or100 mg compound per kg biomass to be treated per 24 hours. For example,effective amounts include at least about 0.05 mg/kg/24 h, 0.1, 0.2, 0.5,1.0, 2.0, 3.0, 4.0, 5.0, 6.0 7.0, 8.0, 9.0, 10, 15, 20, 30, 40, 50mg/kg/24 h, or more; see also Table 2 for non-limiting examples. Forother insect pests, different amounts may be required, which can howeverbe tested without undue experimentation, using for example bioassays.Thus, the effective amount can be determined experimentally, using undueexperimentation. It may vary, depending on the formulation andapplication area. A greenhouse (closed environment) may require loweramounts than a field environment. Importantly, the number of targetpests, such as whiteflies, actually probing the plant tissue contactedwith a composition comprising or consisting of a repellent issignificantly reduced compared to the untreated control plants, wherebythe virus transmission and virus damage is reduced on the treatedplants.

TABLE 2 suitable amounts of insect repellents or attractants, especiallyfor whiteflies volatile compound active compound per 24 h per kg (commonname) biomass (FW) to be treated repellents alpha-curcumene 1-30 mg,e.g. 1.4-28 mg beta-myrcene 0.05-5 mg, e.g. 0.1-2 mg para-cymene 0.05-3mg, e.g. 0.05-1 mg gamma-terpinene 0.1-10 mg, e.g. 0.4-8 mg zingiberene1-60 mg, e.g. 2.8-55 mg alpha-terpinene 0.1-10 mg, eg. 0.5-8 mgalpha-phellandrene 0.01-2 mg, e.g. 0.06-1.5 mg attractantsbeta-phellandrene 0.1-10 mg, e.g. 0.4-8 mg limonene 0.05-5 mg, e.g.0.05-2 mg 2-carene 0.05-3 mg, e.g. 0.05-1 mg FW = Fresh weight

In one embodiment the composition comprising, or consisting of, one ormore repellent compounds simulates the concentrations and/or compoundratios as measured in different, unattractive (repellent) wild tomatoplants (see Table 3 below), but lack other terpene and/or terpenenecompounds found naturally in such plants.

TABLE 3 Ratio of effective compounds tomato line effective compounds inmixture ratio Repellents LA2560 p-cymene:gamma-terpinene:beta-myrcene1:1:4 PI27826 zingiberene:curcumene 1:1.3 LA716p-cymene:gamma-terpinene:zingiberene 1:1:18 LA1340p-cymene:gamma-terpinene:beta-myrcene 1:0.8:4 Attractants S.lycopersicum beta-phellandrene:limonene:2-carene 1:2.4:0.2

Obviously, other amounts and other ratios than those presented in Tables2 and 3 above may be suitably used, e.g. for other insects orinsect-host combinations. The most suitable amounts and/or ratios can bedetermined by the skilled person without undue burden, using for examplebioassays (see below) or field assays.

Whether an amount of one or more active ingredients is an “effectiveamount” for attracting or repelling the target pest (e.g. whiteflies)can be easily tested. For example, the following bioassay may be usedfor whiteflies and/or other target pests. Obviously, similar bioassayscan be devised by the skilled person.

A suitable bioassay involves, for example, the following steps:

(a) providing a plurality of host plants, e.g. tomato cultivars;(b) contacting the plants, either directly or indirectly, with one ormore compounds and/or with one or more concentrations of a compound orcompound-mixture (or compositions comprising these). Indirect contactmay be effected by including a support, such as rubber septa (e.g. SigmaAldrich Z167258) or filter paper disks, to which the compound(s) havebeen added, on or near the plants. For example, rubber septa loaded withone or more volatile compounds may be added to plants (the ‘treated’plants) but not to the controls (the control or reference plants, or‘untreated’ plants). Reference plants are either contacted with acontrol composition (e.g. lacking the active ingredient/s) or are notcontacted with the compound(s)/composition(s);(c) releasing the target insect into the area of the treated anduntreated plants and allowing the insects to settle on the plants;preferably the target insects are released in such a way that no biastowards the treated or untreated/controls results from the releaseitself; also, it is preferred that other cues which could affect insectbehaviour (such as visual cues) are reduced or eliminated, so that thelanding, probing and/or feeding of the insects on the treated anduntreated/control plants is not influenced (or influenced as little aspossible) by other cues;(d) analyzing the plant preference of the insects at one or moretime-points after release (e.g. at 10, 20, 40, 60 minutes, or more,after release) and comparing the number of insects on the treated plantswith the number on the untreated plants.

The data is preferably analyzed statistically in order to determinewhether one or more compounds have an attractant or repellent effect orwhat the most optimal concentration of an attractant or repellentcompound or compound-mixture is. See also the Examples for a suitablebioassay for whiteflies.

Depending on the insect species, the experimental setup may be variedslightly. For whiteflies, for example, preferably at least 50, 100, 150or more whiteflies are given a choice between treated anduntreated/control plants.

Uses According to the Invention

The invention provides the use of one or more of alpha-curcumene,beta-myrcene, para-cymene, gamma-terpinene, alpha-terpinene, alphaphellandrine and/or zingiberene for the preparation of an insectrepellent composition, preferably a sap-sucking insect pest repellentcomposition, most preferably a whitefly repellent composition.

In another embodiment the invention provides the use of one or more ofbeta-phellandrene, limonene and/or 2-carene for the preparation of aninsect attractant composition, preferably a sap-sucking insect pestattractant composition, most preferably a whitefly attractantcomposition.

In yet a further embodiment the use of one or more of the aboverepellent or attractant compositions for repelling or attractingmammalian insect pests, such as mosquitoes (e.g. malaria mosquitoes,yellow fever mosquitoes, and the like), is provided herein. Othermammalian insect pests include, for example, the Scottish biting midgeor other blood-sucking midges. Such compositions, especially repellents,can be used as sprays, creams, solutions, etc. to be applied to e.g. theskin, clothes, fabrics, areas outdoors or indoors, etc. in order toexert their effect. Especially mosquito repellents and/or midgerepellants are provided, which comprise or consist of an effectiveamount of one or more of the seven compounds of Table 1. Followingapplication to the skin or clothes, or to environment (e.g. as anaerosol) where the humans or animals want to reside, or to a carrier orsupport the number of mosquitoes (especially female mosquitoes) issignificantly reduced compared to an untreated control.

The methods for determining the effective amount of one or morecompounds and/or compositions are analogous to those used for plantpests. For example, an analogous assay can be used, comprising e.g.choice assays, whereby the insects are placed into Y-shaped tubes andallowed to move upwind along either branch of the Y. In one tube therepellant or attractant compound is placed and the number of insectsmaking a specific choice is counted. In vivo tests may include

(a) providing a plurality of mammalian subjects;(b) contacting the subjects, either directly or indirectly, with one ormore compounds and/or with one or more concentrations of a compound orcompound-mixture (or compositions comprising these). Indirect contactmay be effected by adding the compound or composition to clothing.Reference subjects are either contacted with a control composition (e.g.lacking the active ingredient/s) or are not contacted with thecompound(s)/composition(s);(c) releasing the target insect into the area of the treated anduntreated subject (or part thereof (e.g. the arm or hand) and allowingthe insects to settle.(d) analyzing the number of bites of the insects at one or moretime-points after release (e.g. at 5, 10, 20, 40, 60 minutes, or more,after release) and comparing the number of insects on the treatedsubjects with the number on the untreated subjects.

Parts of the invention described for plant insect pests thus apply in ananalogous way to mammalian insect pests and where “plant insect pests”are referred to, mammalian insect pests are encompassed analogously,with obvious variations (e.g. support material is preferably clothing,or containers, such as spray-containers, lotion containers, and thelike).

The compositions may be used according to the methods described furtherbelow.

Support Materials Comprising Attractant Compounds or Compositions

In another embodiment the invention provides the use of one or more ofbeta-phellandrene, limonene and/or 2-carene for the preparation of asupport material comprising an insect pest (e.g. whitefly) attractantcomposition. The support material comprising an attractant compound orcomposition according to the invention is also an embodiment of theinvention per se. The material is preferably a container, holder orother solid support onto or into which the attractant composition isplaced. The solid material may be a trap, such as known insect traps.Alternatively, the solid material may be a volatile-dispenser, asdescribed above. The support material may also be a trap plant or aplurality of trap plants, or parts thereof (e.g. a leaf). Preferred trapplants are plant species and/or varieties which are susceptible to thetarget insect (e.g. whiteflies) and which are natural hosts of thetarget insect pest species. For example, cultivated tomato species canbe used, whereby the attractant is applied onto the aerial plantmaterial. Alternatively, materials comprising the attractant (e.g.rubber septa or filter papers) may be added to the plants or between theplants, so that potential phytotoxic effects of the compositions areavoided. By adding the compounds or compositions to the supportmaterial, direct contact between the compound or composition and theplant tissue is avoided.

Any support material may be used. The solid material may, thus, forexample be a filter paper (onto which the attractants is/are applied bye.g. spotting, spraying or dipping) or a rubber or synthetic material,such as rubber septa. The solid material may be made of plastic, solidsynthetic material, polymers, metal, glass, paper, carton, biologicalmaterial (e.g. wood, cork, etc.), or the like. It may be in the form oftubes, disks, blocks, boxes, cubes, beads, (nano)particles or granules,or any other. Suitable rubber septa are for example available fromSigma-Aldrich (Z167258). Semi-solid support materials may be gels (e.g.agar), foams or creams.

Support Materials Comprising Repellent Compounds or Compositions

In yet another embodiment the invention provides the use of one or moreof alpha-curcumene, beta-myrcene, para-cymene, gamma-terpinene,alpha-terpinene, alpha-phellandrene and/or zingiberene for thepreparation of a support material comprising an insect pest (e.g.whitefly) repellent composition. The support material comprising arepellent compound or composition according to the invention is also anembodiment of the invention per se. The material may be a container orother solid material onto or into which the repellent composition isplaced. The solid material may be a slow release material, such as a gelor other matrix or container, which emits the volatiles slowly, over alonger period. For example, solid material may be a volatile dispenser,as described above. The material may also be a crop plant or a pluralityof crop plants. Preferred crop plants are plant species and/or varietieswhich are to be protected from target insect pest (e.g. whitefly)damage. For example, cultivated host species, such as tomato, cotton,Curcubitaceae, potato, etc. can be protected from insect pest (e.g.whitefly) damage by applying the repellent onto the aerial plantmaterial or within the planted field, e.g. on carriers or dispensersplaced at regular intervals throughout the field. Supports comprisingthe repellent (e.g. rubber septa or filter papers) may be added to oneore more of the crop plants or between the plants, so that potentialphytotoxic effects of the compositions are avoided. By adding thecompounds or compositions to the support material, direct contactbetween the compound or composition and the plant tissue is avoided.

Any support material may be used, as described above for attractantsupports.

See also the methods herein below.

Methods for Repelling and/or Attracting Insect Pests Using Compounds orCompositions According to the Invention

A method for reducing infestation of cultivated plants by insect pests,i.e. a method for repelling and/or attracting insect pests such aswhiteflies and/or other insect pests, is provided, comprising the stepsof:

(a) providing a composition comprising or consisting of one or morerepellent compounds selected from S-curcumene, beta-myrcene,para-cymene, gamma-terpinene, alpha-terpinene, alpha-phellandrene and/orzingiberene; and(b) adding said composition one or more times to a plurality of cropplants; and/or(c) providing a composition comprising or consisting of one or moreattractant compounds selected from beta-phellandrene, limonene and/or2-carene, and(d) adding said composition one or more times to one or more trap plantsor trap materials.

The compositions under (a) and (c) are described herein above.Optionally, steps (a) and (b) may be repeated several times. Likewise,optionally steps (c) and (d) may be repeated several times. It is clearthat, when protection of a crop is desired, attractant compositions maybe used separately from repellent compositions, and vice verca, or bothmay be used together, to e.g. repel insects from the crop and attractinsects to the trap, which may for example be located near the crop orinterspersed with the crop. Thus, in essence three methods are provided:(a) protection of the crop by repelling insect pests, (b) protection ofthe crop by attracting insect pests away from the crop plants and (c)using both strategies together for reducing insect infestation of thecrop.

In step (b) the compositions may be added directly to (contacted with)the crop plants or parts thereof, e.g. by spraying onto the plants, byspraying individual plants or leaves or by spot application toindividual leaves, by fumigation, by manual placement of liquid, solidor semisolid formulations onto a plurality of plants or plant parts, bydusting etc. “Direct contact” (i.e. physical contact) between the plantmaterial and the compounds or compositions can, thus, be used.

Alternatively, in another embodiment, “indirect contact” between thecrop plants and the compounds or compositions is used, whereby thecomposition or compound is brought into contact with a support (orcarrier) material first, and said support material (comprising saidcompounds or compositions) is then placed either onto one or more plantsor plant parts, or near the plants, e.g. between rows, between plants orinto/onto the soil where the plants are growing or are to be grown.

The best place of application of the repellents on or near the hostcrop, as well as the frequency of application, depend on a number offactors, such as the architecture and physiology of the crop, the age ofthe crop, the formulation, the insect pest infestation in the area, etc.For formulations which become volatile very quickly, a more frequentapplication may be required to effectively repel the target insectpests, e.g. whiteflies. Similarly, in areas with lots of rainfall, anaerial application may be washed off more quickly, requiring one or morefurther applications or shorter intervals of applications. The skilledperson can easily determine the optimal application frequency forsufficiently reducing infestation. Application may, thus be one or moretimes daily, weekly or monthly or even as low as 1, 2, 3 or 4 times pergrowing season of the crop. In one embodiment the composition comprisingone or more repellent compounds according to the invention may also beapplied to the area where the crop is to be grown prior to seeding orplanting of the crop, so that infestation is already reduced beforeemergence of the seedlings.

Suitable application frequencies may, thus, for example be 1, 2, 3, 4 ormore times between planting and harvest of the crop. The crop may begrown in a closed environment (e.g. a greenhouse or tunnel), asemi-closed environment (e.g. a field crop covered by canvas) or an openenvironment. Crops which benefit from the attractant and/or repellentcompositions according to the invention are of course crops which arenatural hosts to the susceptible insect pests, whose behaviour isaltered by the compounds and compositions described herein. In oneembodiment the crop plants are therefore plant species which are hostsof sap-sucking insects, in particular whitefly. The greenhouse whitefly,Trialeurodes vaporariorum, has a very broad range of host species, suchas most vegetable species and ornamentals. The silverleaf and sweetpotato whitefly (Bemisia argentifolii and B. tabaci) also have a verybroad host range, including most vegetable species.

In a preferred embodiment the crop plants are tomato plants, preferablycultivated tomato. The crop plant may also be a genetically modifiedplant, i.e. a transgenic or cisgenic plant, comprising e.g. a herbicideresistance gene.

Application of the repellent-comprising compositions preferablysignificantly reduces virus transmission, due to the reduction of adultsap-sucking pests, such as whiteflies, and plant tissue probing in thetreated crop. A significant reduction in virus transmission in thetreated crop compared to an untreated crop can, therefore, also be usedas a measure of efficacy of the treatment. Alternatively, the number oftarget insects (e.g. whiteflies) can be counted/estimated, or yieldand/or quality of the crop can be compared between treated and untreatedcrops in order to determine the most effective dosage andapplication-regime of any of the compositions according to theinvention.

One need not apply the same repellent composition two or more times tothe same crop, but an alteration of treatments is also envisaged, as isa combination of treatments. For example, a treatment with a compositioncomprising (or consisting of) one of the seven repellents may be alteredwith, or combined with, a treatment with a composition comprising (orconsisting of) any one of the other seven repellent compounds.Similarly, a treatment with a composition comprising (or consisting of)two of the seven repellents may be altered or combined with a treatmentwith a composition comprising (or consisting of) any one of the otherseven repellent compounds, or consisting of two other repellentcompounds, etc. Thus, in step (a) one may also provide several differentcompositions, which may then be applied in step (b), either together atthe same time, or consecutively.

Similarly, the formulation and/or concentration of the activeingredient(s) provided in (a) and applied in (b) need not be the same.One can, for example increase or decrease the concentration of theactive ingredient throughout the growing season of the crop, e.g.depending on insect pest (e.g. whitefly) infestation or warningsthereof.

In one embodiment, however, the active ingredient(s) provided in (a) andapplied in (b) is/are chemically the same, and are preferably also inthe same formulation and/or concentration.

In a preferred embodiment, the active ingredient(s) is/are slowlyreleased from the composition over a longer period of time. A preferredformulation is, therefore, a slow release, or controlled release,formulation. Such formulations can be made using methods known in theart, for example for pesticides, using (micro)encapsulation, laminatedstrips, polyvinylchloride strips, rubber pellets, etc. or other methodsfor slow and/or controlled release. See e.g. Barlow, F (1985, Chemistryand formulation. In: Pesticide Application: Principles and Practice. Ed:P T Haskell. Oxford Science Publications: Oxford. pp 1-34), Dent, D R(1995, Integrated Pest Management. Chapman & Hall: London, Glasgow,Weinheim, New York, Todyo, Melbourne, Madras), Rombke, J & J M Moltmann(1995, Applied Ecotoxicology. Lewis Publishers: Boca Raton, N.Y.,London, Tokyo) or Ware, G W (1991, Fundamentals of Pesticides. Aself-instruction guide. Thomsom Publications: Fresno USA).

The treatment of the crop with repellents may be combined with thetreatment of plants or areas near the crop with attractants or baitcompositions. Alternatively, the use of attractants or bait compositionsmay in itself be sufficient to protect the crop from insect pest (e.g.whitefly) damage, and in such cases no treatment of the crop itself isnecessary.

The above descriptions for steps (a) and (b) apply also to steps (c) and(d), with the difference that in step (d) the plants need not be cropplants and need not even be of the same species as the crop plant(although they may be). The trap plants may be any species of plant, butpreferably they are plants naturally susceptible to the insect pest(e.g. whiteflies).

The plants may be grown near the crop in order to lure the insects fromthe crop, thereby reducing infestation of the crop. For example, stripsor boarders of trap plants may be grown around one or more edges of thecrop plants. Alternatively, crop plants and trap plants may be grown inparallel rows. Obviously, it is also possible to grow the trap plants indistinct areas within the crop plants, e.g. in the middle of the cropfield.

The same also applies to trap materials, which may be interspersed nearor within a crop field or green house-grown plants. It is preferred thatthe trap plants or trap materials are near enough to the crop plants tolure the whiteflies away from the crop plants. The trap materials may betraditional insect traps to which the compositions according to theinvention are added.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B show the treatment effect of wild-tomato headspace toone plant in a setup of four S. lycopersicum plants (expressed as % ofuntreated setup). empty: empty carriers; pe: carriers containingpentane: ether; pennelli: carriers containing total headspace (collectedover 24 h) of S. pennelli; typicum: carriers containing total headspace(collected over 24 h) of S. habrochaites f. typicum. Bars presentaverages of 3 experiments (±SE).

FIGS. 2A, 2B, 2C, 2D, 2E, 2F, 2G, 2H, 2I, and 2J show the treatmenteffect of a volatile compound (or mix) to one plant in a setup of fourS. lycopersicum plants (expressed as % of untreated setup). A) treatmentwith p-cymene; B) treatment with γ-terpinene; C) treatment withβ-myrcene; D) treatment with mix of p-cymene, γ-terpinene and β-myrcene(“mix”); E) treatment with a-terpinene; F) treatment withα-phellandrene; G) treatment with epizingiberene; H) treatment withS-curcumene; I) treatment with zingiberene; J) treatment withR-curcumene. Bars are averages of 8 experiments (±SE). nt: plants in setup to which no volatiles were added.

FIG. 3 shows relative B. tabaci attraction (%) to 72 introgression-lines(S. lycopersicum cv Moneyberg×S. pennelli LA716) (light bars) comparedto both parents (dark bars; Moneyberg and LA716 respectively). n=3±SE.

The following non-limiting Examples illustrate the different embodimentsof the invention. Unless stated otherwise in the Examples, standardprotocols known in the art are used.

EXAMPLES Example 1 Tomato Head-Space Volatiles and Whitefly Preferences1.1 Material and Methods

A population of Bemisia tabaci was collected at a common greenhouse inSanta Maria del Aguila (Almeria, Spain) in October 2005. By PCR analysesthis population was identified to belong to the Q-biotype. Thepopulation was reared in a climate chamber (Temperature 28° C., 16 hlight) on a mixture of tomato and cucumber plants. Preference of theinsects for particular plants (treated or untreated/control-treated) wastested in free choice bioassays.

It is known that whiteflies make use of both visual cues as well assmell to find their host. It was shown by the inventors that B. tabacican differentiate between different tomatoes using volatile cues byomitting visual cues in a ‘blind’ assay where tomatoes were placed undera mesh cover.

In order to test the effect of scent of the tomato plant onhost-preference of the whitefly the sampled headspace, containing thefull blend of semiochemicals, of the more repellent (as previouslyestablished by the inventors) wild-tomato plants accessions LA716 (S.pennelli), PI27826 (S. habrochaites f. typicum) and PI126449 (S.habrochaites f. glabratum) was applied to a non-repellent/attractiveplant (cv Moneymaker). The seeds were obtained either from 1) the C.M.Rick Tomato Genetic Resource Center (TGCR), Department of PlantSciences, University of California-Davis, One Shields Avenue, Davis,Calif. 95616, United States of America, or from 2) The United StatesDepartment of Agriculture—Agricultural Research Service, Plant GeneticResources Unit, Cornell University, 630 West North Street, Geneva, N.Y.14456, United States of America.

Tomato Headspace Sampling

Volatiles were collected by placing three week old wild-tomato plants ina climatised room in large desiccators for 24 hours, including a 16 hday period. Desiccators were ventilated with carbon-filteredpressure-air at 400 ml min⁻¹. Volatiles were captured on a sampling tubecontaining 300 mg Tenax resin according to Kant et al., (2004). Next,volatiles were eluted off the Tenax with 1 ml pentane:diethylether(4:1). including BA as an internal standard. Identification was achievedby injecting 1 μl of the eluent into an Optic injection port (ATAS GLInternational, Zoeterwoude, NO at 50° C. which was heated to 275° C. ata rate of 4° C./s/The split flow was 0 ml for 2 minutes and then 25 mlmin⁻¹. Compounds were separated on a capillary DB-5 column (10×180 μm,film thickness 0.18 μm; Hewlett Packard) at 40° C. for 3 min and then to250° C. at 30° C. min⁻¹ with helium as a carrier gas. The column flowwas 3 ml min⁻¹ for 2 minutes and 1.5 ml min-1 thereafter. Mass spectraof eluting compounds were generated at 70 eV (ion source at 200° C.) andcollected on a Time-of-Flight MS (Leco Pegasus III, St. Joseph, Mich.,USA) with a 90 sec acquisition delay at 1597 eV, at an acquisition rateof 20 spectra sec⁻¹.

Sample identification and quantification was based on synthetic externalstandards of of known concentration (Fluka, Mich., USA). Each tomatoaccession was measured 6 times. Additionally, a 1 ml sample(pentane-diethylether containing tomato volatiles) was used toimpregnate filterpaper cards (Whatman, 25 mm diameter) to be used inbioassays with B. tabaci.

Free-Choice Bioassays with B. tabaci and Tomato

Free choice experiments with B. tabaci were carried out in a greenhousecompartment (28° C., RH 65%). Light was supplied by high-pressure sodiumlamps (Hortilex Schréder SON-T PIA GP 600W) with a radiation of 250W/m². The preference behaviour of B. tabaci biotype Q (Almeriapopulation) and biotype B (labculture Netherlands) was compared inbioassays with different wild tomatoes (LA1777, LA2560, GI1560) and S.lycopersicum cv Moneymaker). Plants were placed inside a plastic coveredwooden tray (170×100×20 cm) filled with soil, at equal distance fromeach other. Two hundred adult whiteflies were captured, placed at 4° C.for five minutes and then released in the middle of the setup. Ten and20 minutes after release, the number of whiteflies on each plant wasrecorded. Since no differential behaviour between B. tabaci B and Q wasfound, all further bioassays were done with the Almeria (Q) population.

For bioassays with headspace (total headspace or single compounds) fourpotted tomato plants (S. esculentum cv Moneymaker) were placed in asquare setup at a distance of 50 cm. One hundred and fifty adultwhiteflies were released and recorded as described above. To test theeffect of selected headspace components on repellence, syntheticstandards (FLUKA) were applied to either 10 filter-papers discs(Whatman, 25 mm diameter) or 10 rubber septa (Sigma Aldrich, Z167258).Prior to loading, the septa were placed in CH₂Cl₂ for 24 h and air-driedfor 3 days (Heath et al., 1986). The paper discs or septa containingvolatiles were attached to one of the four plants with metal wire. Theposition of the treated tomato was randomised. Five minutes afterplacing the volatiles on the plant, whiteflies were released. For eachcomponent at least 8 replications were carried out. Treatments wereadministered in a setup in which compounds were always added to the sameplant in comparison to 3 plants with empty carriers. Prior to each assaywith volatiles, the experiment was done with the 4 plants in anuntreated setup, in the same position to allow comparison in the samebackground.

1.2 Results

Results are shown in FIG. 1. These assays showed that the tomatocultivar Moneymaker can be made up to 60% less attractive when the totalheadspace components that make up the scent of a more repellent tomatoaccession is added to the plant's headspace, compared to its backgroundsmell. Pentane-ether, the solvent in which the headspace was eluted, wasshown not to have any effect on repellence/attraction.

Example 2 Determination of Headspace Components Involved in B. tabaciRepellence 2.1 Material and Methods.

A collection of 16 wild type and 5 cultivated tomatoes was put together(Table 4). For each of these cultivars the level of whitefly repellencewas established in randomised hexagon setups in free choice bioassays inan open greenhouse. In each experiment 300 new naive, adult whiteflies(Almeria population) were released in the middle of 6, randomly chosen,plants Twenty minutes after release the number of flies on each plantwas counted. Each setup was repeated 3 times after which the two leastrepellent plants were replaced by two new test plants. Stepwisesequential testing finally resulted in a ranking into 7 classes with aclear differential repellence (Table 4).

The headspace of 16 wild tomatoes and 5 cultivated tomatoes (Table 4)was collected. Undisturbed 3-weeks old tomato plants were transferred to40-L desiccators. The headspace was sampled during 24 h including a 16 hlight period, by trapping of the volatile components as described above.The GC-MS analysis resulted in a unique ‘fingerprint’ of volatilecomponents for each of the tomato accessions. Each accession was sampled6 times.

2.2 Statistical Analysis

In a statistical analysis the correlation between the identifiedcomponents of the tomato headspace and the ranking of whiteflyrepellence measured in the bioassays was made. Using two approaches, astepwise-linear regression analysis and a MANOVA, 8 volatiles wereidentified to be correlated to whitefly repellence, whereas 24 othervolatile compounds were eliminated as non-relevant for repellency orattraction.

2.3 Results

TABLE 4 Repellence ranking of 16 wild and 5 cultivated tomato accessionsto B. tabaci, on a scale of 1-7, whereby 1 refers to highest repellentand 7 refers to least repellent/most attractant. tomato accession rankS. pennelli LA716 2 LA1340 2 LA2560 1 S. habrochaites LA1777 3 f.typicum PI27826 1 PI27827 3 LA1353 3 S. habrochaites PI126449 4 f.glabratum PI134417 3 PI134418 4 PI251304 3 IVT701631 4 LA407 5 GI1560 3LA1840 5 S. peruvianum LA1708 5 S. lycopersicum cv Motelle 6 cv Mogeor 6cv Monalbo 6 cv Moneymaker 7 cv Pitenza 6

It can be seen from Table 4 that the headspace of cultivated tomato (cv)are the least repellent/most attractant to whitefly, while the headspaceof wild tomato accessions is more repellent.

The compounds responsible for repellency or attraction of whitefly wereidentified and are shown in Table 5. Beta-myrcene, p-cymene,alpha-phellandrene, alpha-terpinene and gamma-terpinene are repellentcompounds linked to S. pennelli whereas S-curcumene and 7-epizingibereneappear to be responsible for rendering the S. habrochaites (formertypicum) more unattractive. Beta-phellandrene, limonene and 2-carene aresignificantly correlated to the more attractive cultivated S.lycopersicum plants.

TABLE 5 Identified semiochemicals associated to B. tabaci repellence orattraction. Significance of effect on B. tabaci behaviour inchoice-assays and responses of B. tabaci antennae to the varioussemiochemicals (mV) behavioural antennal source terpenoid associationeffect response S. pennelli p-cymene repellence *** 2.4 S. pennelliα-terpinene repellence * 4.1 S. pennelli α-phellandrene repellence * 2.2S. habrochaites 7-epi repellence *** 2.3 f. typicum zingiberene S.habrochaites S-curcumene repellence ** 5.0 f. typicum

TABLE 1 Accessions of wild tomato (S. pennelli, S. habrochaites and S.peruvianum) and cultivated tomato (S. lycopersicum) ranked based onrelative repellence to B. tabaci. 1 = highest repellence; 7 = leastrepellence. Semio-chemicals (μg 24 h⁻¹ {grave over ( )}10 g⁻¹ FW)related to repellence emitted by wild tomato and cultivated tomato, incomparison to caryophyllene which is present in all accessions. Valuesindicate means (±SE) (n = 6). Tomato Accession rank β-myrcene p-cymeneγ-terpinene curcumene zingiberene caryophyllene S. pennelli LA716 2 —0.34 ± 0.13 4.01 ± 1.71 10.83 ± 8.29  68.5 ± 58.9  0.55 ± 0.20 LA1340 21.46 ± 0.45 0.35 ± 0.11 2.49 ± 0.96  4.46 ± 4.35  6.56 ± 6.56  2.01 ±0.82 LA2560 1 1.36 ± 0.61 0.47 ± 0.18 5.88 ± 2.50  3.64 ± 3.09  8.44 ±4.36  3.06 ± 1.50 S. habrochaites LA1777 3 0.12 ± 0.10 0.05 ± 0.04 0.06± 0.07  12.3 ± 10.8  9.71 ± 9.14  7.39 ± 3.36 (f. typicum) PI127826 1 —— 0.24 ± 0.24 282.4 ± 116.2 521.0 ± 323.6  0.28 ± 0.18 PI127827 3 0.01 ±0.01 0.03 ± 0.03 — — —  0.34 ± 0.21 LA1353 3 0.20 ± 0.12 0.01 ± 0.01 — ——  2.56 ± 0.84 S. habrochaites PI126449 4 — — 0.22 ± 0.22 — —  8.34 ±2.61 (f. glabratum) PI134417 3 — — — — — 13.41 ± 5.98 PI134418 4 — — — ——  3.08 ± 1.10 PI251304 3 — — —  0.21 ± 0.21 —  7.23 ± 2.81 IVT701631 4— — —  3.35 ± 3.21 —  7.27 ± 6.31 LA407 5 — — —  0.96 ± 0.96 —  3.64 ±0.92 GI1560 3 — — —  11.1 ± 6.6  3.76 ± 3.76  3.48 ± 0.57 LA1840 5 0.02± 0.02 0.01 ± 0.01 0.05 ± 0.05  0.08 ± 0.05  0.88 ± 0.88  0.12 ± 0.05 S.peruvianum LA1708 5 0.09 ± 0.09 0.07 ± 0.03 1.13 ± 0.68  0.54 ± 0.54 — 2.88 ± 0.86 S. lycopersicum Motelle 6 0.08 ± 0.06 0.02 ± 0.01 — — — 0.54 ± 0.17 Mogeor 6 0.08 ± 0.05 0.06 ± 0.05 — —  0.38 ± 0.38  2.24 ±0.91 Monalbo 6 0.42 ± 0.15 0.10 ± 0.05 0.60 ± 0.22 —  0.51 ± 0.34  1.37± 0.11 Moneymake 7 0.07 ± 0.07 0.01 ± 0.01 0.07 ± 0.07  0.11 ± 0.11 — 3.35 ± 2.41 Pitenza 6 0.17 ± 0.10 0.07 ± 0.04 0.07 ± 0.07 — —  1.11 ±0.21

Example 3 Bioassays with Selected Components and Mixtures of theseComponents 3.1 Material and Methods

β-phellandrene, zingiberene and curcumene were not commerciallyavailable and had to be synthesised. Zingiberene and R-curcumene wereisolated from ginger oil and 7-epi zingiberene and S-curcumene from S.habrochaites (PI27826) leaf material after Millar (1998, J. Nat. Prod61, 1025).

Host preference with and without manipulated headspace by B. tabaci wasexplored in free choice assays. In each setup four cultivated tomatoes(cv. Moneymaker) were tested as described earlier. For the bioassayswith volatiles rubber septa (Sigma Aldrich Z167258) were extracted withCH₂Cl₂ for 24 hours and dried to the air for 3 days. The desired blendof volatiles was added to the rubber septa in 100 μl hexane. Bioassayswith pure components, or mixtures of pure components were carried out asdescribed above.

3.2 Results

To positively confirm the correlation between the 7 candidate componentsand B. tabaci behaviour, host preference was assayed in bioassays withpure components. The desired (blend of) pure volatile chemicals wereadded, as described above, to the Moneymaker background on filter papercards. In the absence of foreign volatiles the percentage recaptured B.tabaci on each of the four Moneymaker plants did not deviatesignificantly from the expected 25% (data not shown). However, when oneof the plants was treated with 10 μg p-cymene, the level of attractionof this plant decreased significantly, compared to the same plant in theuntreated setup. The percentage of whiteflies visiting the treated plantdecreased with 44% on average (p<0.001)(FIG. 2A) while the untreatedplants harboured increased numbers of B. tabaci. In general, when asynthetic component had a repellent effect on B. tabaci, the plants withempty carriers became increasingly more attractive (FIG. 2). Applicationof γ-terpinene to the Moneymaker background appeared to improverepellence, though no significant behavioural effect was established(p=0.102) (FIG. 2B). To assess whether the sum of these three componentswould yield a greater effect than p-cymene alone, a mixture of p-cymene:γ-terpinene: β-myrcene in the same ratio as found in accession LA2560(1:12:3) was tested. This resulted in decreased plant visits with 45% onaverage (p<0.001)(FIG. 2D). Additional monoterpenes, derived from theIntrogression-line analyses, a-phellandrene and a-terpinene bothdecreased tomato attractiveness significantly (p=0.030 and 0.014,respectively) (FIG. 2E,F). Finally, both sesquiterpenes tested,tomato-derived epizingiberene as well as its oxidation productS-curcumene, also had a clear repellent effect (p<0.001) (FIG. 2G,H).

Example 4 Linking Tomato Volatiles Directly to B. tabaci Response

Electroantennography (EAG) was employed to confirm the responsiveness ofthe atennae to 10⁻³ dilution in paraffin oil (Uvasol, Merck) of thechemicals described. Small pieces of filter paper (2 cm2; Schleicher &Schuell, Dassel, Germany) were soaked with 100 μl of the standarddilution or praffin oil only (control). The filter paper was insertedinto a 10-ml glass syringe (Poulten & Graf GmbH, Wertheim, Germany). Areproducible stimulus was supplied by puffing 5 ml of air over theantenna (Schutz et al., 1999). The EAG response was recorded for eachstandard (10⁻³) dilution. The response to paraffin oil was considered asa negative control and was subtracted from all the reported EAGmeasurements. The EAG response expressed as a potential differenceacross the electrodes (in mV) for the different pure chemicals is givenin the right-hand column of Table 5.

Example 5 Bioassays in an Introgression Library

Because of the interesting repellence levels found in the S. pennelliaccessions an introgression library (parents S. pennelli LA716×S.lycopersicum cv Moneyberg) was subsequently screened in bioassays (FIG.3). Several lines with significantly decreased attraction compared tothe susceptible parent, were selected. The headspace composition ofthese selected lines as well as the Moneyberg-parent were identified.Concentrations of α-phellandrene, α-terpinene and p-cymene weresignificantly higher in the selected lines compared to Moneybergheadspace.

1. A whitefly repellant composition, comprising as active ingredient amixture of two or more repellant compounds selected from the groupconsisting of para-cymene, gamma-terpinene, alpha-terpinene,alpha-phellandrene and/or epizingiberene, wherein the composition issubstantially free of other terpene or terpenoid compounds.
 2. Thewhitefly repellant composition according to claim 1, comprising asactive ingredient a mixture of three or more of the repellant compounds.3. The whitefly repellant composition according to claim 1, wherein thecomposition comprises epizingiberene.
 4. The whitefly repellantcomposition according to claim 1, wherein the composition comprisespara-cymene.
 5. The whitefly repellant composition according to claim 1,wherein the composition comprises gamma-terpinene.
 6. The whiteflyrepellant composition according to claim 1, wherein the compositioncomprises alpha-terpinene.
 7. The whitefly repellant compositionaccording to claim 1, wherein the composition comprisesalpha-phellandrene.
 8. The whitefly repellant composition according toclaim 1, wherein active ingredient of the composition consistsessentially of no more than two of the repellant compounds.
 9. Thewhitefly repellant composition according to claim 1, wherein activeingredient of the composition consists essentially of no more than threeof the repellant compounds.
 10. The whitefly repellant compositionaccording to claim 1, wherein active ingredient of the compositionconsists essentially of no more than five of the repellant compounds.11. The whitefly repellant composition according to claim 1, wherein thecomposition is a volatile liquid.
 12. The whitefly repellant compositionaccording to claim 1, wherein the composition is selected from the groupconsisting of emulsified concentrate formulations, high concentrateliquids, spray concentrates, ultra-low volume concentrates, lowconcentrate liquids or oil solutions, flowable liquids, water solubleconcentrates, encapsulated formulations, dust formulations, granules,wettable powders, soluble powders, liquefied gas, fumigants, andaerosols.
 13. The whitefly repellant composition according to claim 1,wherein the composition is a slow- or controlled-release formulation.14. The whitefly repellant composition according to claim 1, wherein thecomposition is comprised in a solid support material.
 15. The whiteflyrepellant composition according to claim 1, wherein the repellantcompounds are chemically synthesized or purified from natural sources.16. The whitefly repellant composition according to claim 1, wherein thecomposition is not a naturally occurring head-space composition ofplants.
 17. The whitefly repellant composition according to claim 1,where active ingredient accounts for at least 5% weight pre volume ofthe composition.
 18. The whitefly repellant composition according toclaim 1, wherein the composition is adapted to reduce whiteflyinfestation or damage by at least 30%, as measured by number ofwhiteflies, numbers of whitefly eggs laid, number of whiteflies probingplant tissues, virus transmission or incidence, plant yield loss, orplant tissue damage.
 19. A kit comprising (a) a whitefly repellantcomposition comprising as active ingredient one or more repellantcompounds selected from the group consisting of para-cymene,gamma-terpinene, alpha-terpinene, alpha-phellandrene and/orepizingiberene, and (b) a whitefly attractant composition comprising asactive ingredient one or more attractant compounds selected from thegroup consisting of beta-phellandrene, limonene and 2-carene.
 20. A cropfield comprising (a) a plurality of crops and a whitefly repellantcomposition applied on the crops, wherein the whitefly repellantcomposition comprises as active ingredient one or more repellantcompounds selected from the group consisting of para-cymene,gamma-terpinene, alpha-terpinene, alpha-phellandrene and/orepizingiberene, and (b) a plurality of trap plants and/or trap materialsand a whitefly attractant composition applied on the trap plants and/ortrap materials, wherein the whitefly attractant composition comprises asactive ingredient one or more attractant compounds selected from thegroup consisting of beta-phellandrene, limonene and 2-carene.